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Double Comparative - Glossary of Terms
Double Comparative
In general, the comparative form of an adjective or
adverb can
be formed by adding the suffix "-er" or by placing "more"
before. This is covered in more detail in the lesson
"Comparatives". Adding "er" or using
"more" to a word that is already a comparative is called a double
comparative. This is a mistake.
Examples:
She is much more
wiser these days.
(should be just "wiser") Adam is more
better in my opinion.
(should be just "better")
Interactive example:
I prefer the Ireland - it's less windier. [show
me the double
comparative]
Glossary of Grammatical Terms
She is much more
wiser these days. 
(should be just "wiser")